So.. Haven't had a chance to poke Matt about it.. I know he's busy as hell so I hence to just leave him be..

However, this is rather interesting :P

Last few months I've been having braking issues, for the longest it boiled down to feeling like I had no brakes. Grant it I had upgraded Rotors and Heavy Duty pads.. Still the feeling existed. Well I got this clever idea that I would just end up buying a new front Brake System (Calipers, SS Lines, Rotors). No matter what I did it wouldn't stop. You could run it hard, hit the brakes, she would shake like a warped rotor. Altho they weren't warped

Today I decided to try something before I went off and spent XXX's on parts.. Some off the wall thinking.. I loaded up one of my Street files from Eric. Took the truck out and ran it hard, slamming on the brakes like I was a new driver.. The brakes bit harder and stopped faster now. That threw me off, I loaded up Matt's file again, went back to the same thing.. My braking went to hell..

I've conversed with some of my contacts, as well as Eric, we've never heard of Tuning that would affect the Master Cylinder.. However it's apparent in

Stock (No issue)
Street from Eric (No issue)
Hybrid Race from Matt (No issue)
UltraComp (Major Issues)
60hp from Dfuser (No issue)

This is running it between 20-70mph, from soft braking to HEAVY braking. Weird because I've had the same UC file for bout 7 months.. It's been my main file.

So.. Does anyone know how to read the Caliper Pressure while driving? Is there any way? I hate to think this file is done for now.. Not sure, nor is any of my buddies sure, why it's doing it..

Any other UltraComp guys notice anything different with their Files?

 

Maybe your going too fast in the UltraComp tune. These trucks don't stop very well at 250 mph! lol

 

LOL I took that into consideration.. All braking tests were done at same speeds.. 20mph, 40mph, 60mph, 75mph.. All the others were fine except for UltraComp.. It was almost like the calipers weren't grabbing hard enough that they were skipping along the slotted rotors.. Best way I can explain it.. I could lock it up, pedal to floor, I'd feel like I wasn't exactly stopping right away. With the other files I can slam it to the floor and she'll go nose down on you and throw you back when it fully stops..

 

It kinda seems to me that your almost describing the ABS kickin in and taking over with the "It was almost like the calipers weren't grabbing hard enough that they were skipping along the slotted rotors.. ", while your trying to lock em up. If that makes sense. just my .02

 

You would need to Tee in a transducer in your brake lines. It would need to be something on the order of a 12v 4-20ma 0-2000 psi rating. The newer trucks can produce over 1850 psi in the braking system.

 

What do you think about this?

Maybe the motor is not returning to idle when you let off the pedal. Try shifting to neutral before you apply the brakes.

ab

 

At what point in the test did you apply alcohol to the driver?

Other than that, if it's anything, it would have to be the ABS going ballistic. Nothing mechanical could be affected by the tune, right? Log some data and do some checks on some basic readings. It'll give you food for thought if nothing else... Good luck on this one, bud!

 

I'll give those a shot.. What's throwing it off is the shaking.. It shakes as if the rotors were warped, and they aren't.. If they were warped it would occur on any tune including stock.. I'm not a brake expert, so my question is, how does the Master Cylinder produce its PSI for the braking. Is it a work of the Engine? I've been going over everything trying to figure out what in a Tune file would cause the Master Cylinder to act up..

The braking is a combination of full lock and moderate braking. I've simulated emergency brake scenarios and just standard driving..

What I have noticed is a pull to the right on braking which would indicate a bad caliper. However again it's not present on any other Tune or Stock.. Seems to be tied into this Ultra Comp file.. Which has me stumped, I can't recall for the life of me if it was present in the initial trial of the file many many months ago.

Again I end up in the same place.. What in the world could be modified in the programming to affect the Master Cylinder.. I've gone over the programming software for the last few hours and I can't find ANYTHING that relates to the Master Cylinder.

ABS works, thats for sure.. I can't lock up the 35's ever.. Even holding the pedal to the floor..

 

Problem with that is the parameters I can monitor.. Nothing has to do with the brake system. Unless someone can shed some light on what might affect the Master Cylinder, I don't know what to look at..

I know the ABS will keep the wheels from locking completely, but I don't think it would make the brakes feel like it's skipping.. It almost feels like every time it hits a Slot in the rotor (Slotted Rotors), it bounces off the rotor and back on.. Which makes absolutely no sense to me LOL.

One thing I have noticed, if I roll the throttle and take off with UltraComp, than hit the brake fast simulating someone pulling out infront of me.. It's almost like I have NO BRAKES. But if I do the same thing cruising and than hit it, it will start to slow down but not nearly to the point the other files/stock show.

I'm wondering if the TC Lockup Matt has could play a roll? I know it doesn't unlock until 1500rpms, than it dies down to idle. It was his way of simulating engine braking, however that should help, not make it worse you would think?

 

TC lock should be helping, I agree. Have you thought of the power assist aspect? What, if anything could be happening to the vacuum? I'm stretching a bit I know, but there IS something creating this phenomenon. There's a cause to this effect... Log data on MAP, MAF (engine load) and any other related value. You may come out of it with some useful information after that data is evaluated.

 

True.. I'll log it tomorrow and review it.. I got gurls lined up waiting on me LMAO.. It's Friday.. Beer Thirty LMAO

I miss the smoke and EXTREMELY loud noise of the Ultra Comp :-P

 

The only thing on your brake system that could be causing this is the ABS system, and what you are describing (my guess) is the pressure modulation of the system. For some reason (program related) your losing some of your line pressure on the ultra comp tune, hence the harder pedal pressure required and the strange pedal feel (pulsation).

The next step is to find out why the UC program is affecting the ABS parameters.

Have Fun !!!!!

 

I'm not feeling ABS Pulsation in the pedal.. I'm feeling it in the steering wheel from the wheels.. Much like you would with warped rotors..

 

I was thinking the same thing........

 

Hmm, that was my next question. Im going to follow this Post close, if your not feeling it in the pedal. Then im not sure.


Thats what makes this site so great, somebody has this problem im sure.